Synchronizing devices for twin-cylinder heat engines having two opposed pistons in each cylinder



P. PANHARD 3,182,895 SYNCHRONIZING- DEVICES FOR TWIN-CYLINDER HEAT ENGINES HAVING May 11, 1965 Filed Dec. 23, 1965 Nh mm /2 $74 & (N Wmw. Wm. h N R mm m WNW NW WM. J W Nb w E @N @N P Q Q m 1 @N W T mw N N .3 Q Mmn r &\N NN N N United States Patent 7 4 Claims. (or. ass-s6 This inveniton relates to devices of the type used to synchronize the motions of the driving pistons in twincylinder heat engines having two opposed driving pistons in each cylinder, said pistons being so associated and coordinated that one pair of pistons be moving simultaneously towards each other when the other pair are moving simultaneously away from each other, and vice versa. The invention has most notably for its object synchronizin'g devices utilized with engines driving reciprocating pumps wherein each driving piston is coupled to a pump piston. By the term driving pistons used herein is to be understood pistons which bound the engine combustion chambers, in order to distinguish them from the other pistons to be referred to hereinafter.

It is the chief object of the invention to provide synchronizing devices so devised'that they subject the driving pistons only toiaxial loads and that the mechanical friction involved be reduced to a minimum.

A synchronizing system according to the present in- 7 3,182,895 Patented. May 11, 1965 ICC cycle, preferably with precompression in the crankcases 7a, 7b, 8a and 8b.

In what follows, symmetrical parts associated to each engine cylinder 1 or 2 will be designated by the same reference numeral, followed by the letter a or b according as the parts are positioned to the left or the right of FIGURE 1. In order to simplify the description, these letters will be dispensed with as far as possible, driving pistons 5a and 5b, for instance, being then designated simply as the pistons 5.

Driving pistons 3 and 5 are provided with rods 9 and i 10, respectively, through which they are coupled to the vention is accordingly characterized in that it consists in' causing each driving pistonto actuate a synchronizing piston sliding in an individual cylinder which it divides into two chambers, thereby providing for engine synchronization four pistons and four cylinders of identical size, and hence eight chambers, in interconnecting said chambers in pairs through transfer conduits each of which is connected across two chambers which are respectively expanding and contracting at any given instant during the engine cycle, the two chambers of each synchronizing cylinder being thereby connected separately to two cham bers belonging respectively to two other synchronizing cylinders, and in filling with a virtually incompressible fluid each transfer conduit and the two chambers interconnected by the same.

Other objects of the invention together with the foregoing will be set forth in the following description of the preferred method of application (to reciprocatingpump engines), and the preferred embodiments of means for practicing the same, which are illustrated in the drawing accompanying and forming part'of the specification.

It is, however, to be understood that the embodiments disclosed in said description and the drawing are not to be taken as limitations of the invention, as variations may be adopted of the preferred forms within the scope of the invention. a

Referring to the drawing filed herewith:

FIGURE 1 shows in'fragmental elevation and'fragmental section a motor-pump set of which the motor or engine is synchronized by a device according to the inven- Cylinders 1 and 2 are juxtaposed parallel with eachothen in a saine bl ock'. Said engine operates on the two stroke pistons of reciprocating pumps 11 and 12 whose suction conduits 13 draw liquid from a common tank and whose delivery conduits 13 draw liquid from a common tank and whose delivery conduits l4 convey the same under pressure to at least one common driven machine, the outlet port therefrom being connected to said tank whereby to form a closed circuit. Both the output and the pressure ofsaid pumps, the pistons of which have a constant stroke, are preferably regulated in accordance with the specification of, and the drawing accompanying, the patent application filed in France by the applicant on December 15, 1962 in respect of Improvements In or Relating to Variable-Ratio Hydraulic Transmissions, More Particularly for Motor Vehicles."

- The driving pistons in such an engine are so synchronized and coordinated thatthe two driving pistons 3 of cylinder 1 be moving towards each other symmetrically when the two driving pistons S'of cylinder 2 are moving symmetrically away from each other, and that, as is use purely mechanical synchronizing means (utilizing cranks and connecting-rods, rockers, or racks and pinions) which had the drawbacks of subjecting the driving pistons to transverse loads and of dissipating energy through friction; 1 7

' In accordance with the invention, each driving piston actuatesa synchronizing piston sliding in an individual cylinder which it divides into two chambers; More specifically, each driving piston 3-actuates a synchronizing piston 15 sliding in a cylinder 17 which it divides into aso-called inner. chamber 19 and a so-called outerchamber 21, and each driving piston 5 actuates a synchronizing piston 16 sliding in a cylinder-18 which it diprovided with a rod of equal diameter which extends throughthe two end closures of synchronizing cylinders 17 and 18 respectively. Said cylinders are accordingly disposed between engine cylinder 1 (or 2) and the com-j panion reciprocating pump 1l"(or 12), in such manner that the synchronizing pistons 15 and 16 be supported by said rods 9 and 10. a Lastly, the four inner chambers 19 and 20 and the four outerchambers 21 and ZZ-are interconnected in pairs M through transfer conduits each of which extends from a chamber that is expanding -(i.e. chambers 19' and 22) to I a chamber that is contracting (i.e. chambers-.20 and 21) at anygiven instant during the engine cycle (which, in the case of the examples specified between parentheses, is the instant corresponding. to the. specific positions and direc-, tions of motion shownin FIGURE 1).,the-two chambers of each synchronizing cylinder being thus respectively 3 connected to two chambers belonging to two other synchronizing cylinders.

Referring now to the accompanying drawings, the form of embodiment shown thereon comprises two transfer conduits 23a and 23b respectively interconnecting the mutually most closely spaced pairs of outer chambers 21a, 22a and 21b, 22b, and two cross-connected transfer conduits 24 and 25 interconnecting the mutually most distantly spaced pairs of inner chambers 19a, 20b and 19b, 20a, the engine cylinders 1 and 2 being assumed to be juxtaposed as stated precedingly.

A for all practical purposes incompressible fiuid is used to fill each enclosed space formed by a transfer conduit and the two chambers interconnected thereby, namely enclosed spaces 21a, 22a, 23a; 21b, 22b, 23b; 19a, 20b, 24; 19b, 20a, 25. It will be manifest that, provided said enclosed spaces be exempt from leakage or expansion, the four driving pistons will be synchronized, since movement of any driving piston will resut in the displacement through all the transfer conduits of a volume of liquid proportional to the magnitude of said movement, and hence in invariably equal movements in the required direction of both synchronizing pistons and the driving pistons.

As the arrows in FIGURE 1 show, for example, a shift of driving piston 3a towards the left of FIGURE 1 will cause liquid to be transferred by degrees from chamber 21a to chamber 22a (equivalent to a rightward shift of driving piston 5a), from chamber 20a to chamber 1% (rightward shift of driving piston 3b), from chamber 21b to chamber 22b (leftward shift of driving piston 5b) and from chamber 20b to chamber 19a, thereby closing the loop. When driving piston 3a moves rightwardly, the directions of displacement of the driving pistons and of flow of the synchronizing liquid are reversed, but the manner of operation remains unchanged.

In order to allow for possible leakage and expansion in the enclosed spaces hereinbefore defined, the synchronizing means described precedingly are associated to a set of distributing members which operate in dependency upon the positions of synchronizing pistons 15 and 16 in their respective cylinders 17 and 18 and which are so adapted that, when any one of these pistons oversteps its normal end-of-stroke position, the synchronizing chamber that attains its minimum volume at that instant be connected to a source of pressurized liquid, and the synchronizing chamber that consequently exceeds its maximum volume be connected to a discharge space.

The source of pressurized liquid consists of a pump 26 and the discharge space of a tank 27 from which said pump draws the liquid.

As FIGURE 1 clearly shows, the distributing members are valves spring-loaded into the closed position and so adapted that, in the specific case of the valves 28 connected to the delivery conduit 29 of pump 26, they be opened by the pressure contact of pistons 15 and 16 when the same reach the end of their stroke (in the direction of the arrows) and, in the case of the valves 30 connected to the tank or discharge space 27 through at least one conduit 31, by pressure contact with abutments 32 rigid with the rods 9 and of pistons and 16 when the same reach the end of their stroke. Valves are preferably positioned in the upper part of the corresponding chambers.

Reference to FIGURE 2 shows that, in an alternative embodiment, the distributing members are constituted by the synchronizing-piston rods which accordingly embody, firstly, grooves 33 adapted to give each companion chamber such as 21a port in the delivery conduit 29 through the agency of passages 34 which are fixed with respect to the synchronization cylinders such as 1711, and, secondly, grooves 35 adapted to give the other companion chambers such as 19a port in the outlet conduit 31 through the agency of passages 36 which are fixed with respect to said synchronization cylinders, such port being provided when the synchronizing pistons such as 15a reach one end of their stroke. Instead of having direct port in the chamber such as 1911, groove 35 cooperates with a duct 37 having port in said chamber near the top thereof.

In comparison with the embodiment of FIGURE 1, that of FIGURE 2 offers the advantage of dispensing with the need for extra moving parts, of eliminating mechanical shock loadings and of enabling the synchronization chambers to be supplied progressively.

The synchronizing means hereinbefore described function in the following manner.

If it be assumed, for instance, that the piston 16a reaches the end of its rightward stroke (direction of the arrow) with a lead over the other synchronizing pistons, said piston 16:! will open valve 28 (or cause the corresponding groove and passage to come into register in the alternative embodiment of FIGURE 2), thereby admitting the liquid under pressure into chamber 20a from conduit 29. This liquid penetrates into chamber 20a and thrusts piston 16a leftwardly, this being possible since the abutment 32 will have opened discharge valve 30 of chamber 22a at the same time as said piston opened the inlet valve 28. Piston 16a will thus be recentered relative to its counterpart piston 1512.

If it now be assumed that piston 16a is leading piston 15a during its return stroke (in the opposite direction of the arrow), this would indicate that the quantity of liquid contained in chambers 22a and 21a is a little too small. Compensation cannot take place during this return stroke because chamber 22a comprises only one discharge valve 30, but will take place in the course of the next half-stroke through the medium of piston 15a which, being compulsorily in the lead over piston 16a since the volume of liquid under pressure is too small, will open the supply valve 28 before the piston 16a has reached the end of its rightward stroke.

Any possible staggering between the pistons is thus compensated whenever the same tend to overstep the stroke assign-ed to them. Such a disposition additionally allows, prior to each start-up and without any form of complication, of synchronizing the pistons and fully draining the synchronization system if necessary. It will sufiice to that end to deliver liquid under pressure into the cylinders of pumps 12, thereby moving the pistons 16 towards each other. When the same reach the end of their strokes they open the valves 28, which in turn fill the chambers 20, followed, through conduits 24 and 25, by the chambers 19, thereby causing the pistons 15 to move away from each other. On reaching the end of their strokes, pistons 15 open valves 28, thereby admitting liquid under pressure which fills the chambers 21 and then flows through ducts 23 to fill the chambers 22. When pistons 15 and 16 reach the end of their strokes, the abutments 32 lift the valves 30, thereby completely draining the system.

To turn over the engine for the purpose of starting it, it will sufiice to quickly introduce liquid under pressure into the pump cylinders in order to propel the pistons 3 towards each other and cause the mixture compressed thus to be fired as the pistons reach the end of their stroke, thereby producing the first explosion.

It will be noted from FIGURE 1 that, when the engine is started, the first explosion will invariably take place in cylinder 1, as the synchronization chambers associated to chamber 2 serve to drain air from the syna.

tion, but that changes may be made within the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a twin cylinder heat engine having a first cylinder and a second cylinder and two opposed driving pistons in each of said cylinders with the two driving pistons of one cylinder adapted to move simultaneously toward each other while the two driving pistons of the other cylinder are moving simultaneously away from each other and vice versa, a device for synchronizing the motions of said pistons which comprises, in combination, a pair of synchronizing cylinders disposed in line with each of the heat engine cylinders, on opposite sides thereof, a synchronizing piston in each of said synchronizing cylinders, means for rigidly connecting each of said synchronizing pistons with a corresponding heat engine piston, respectively, so as to divide each synchronizing cylinder into two chambers, a first one and a second one, transfer conduit mean-s forming a constantly open communication between one chamber of each synehronizing cylinder located on one side of one of said 6 two pairs of pumps disposed in line with said heat eng-ine cylinders, the two pumps of each pair on either side of one of said heat engine cylinders, respectively, and a common piston rod for each heat engine piston, the synchronizing piston and the pump piston correspondin g thereto.

3. A synchronizing device according to claim 1 further comprising a source of said incompressible liquid under pressure, conduit means in communication with said source, conduit means for the discharge of said liquid and valve means adapted to be operated by said synchronizing pistons, for connecting said chambers with said conduits to adjust the amount of said liquid in said chambers.

44' A synchronization device according to claim 1 furthr comprising a source of said incompressible liquid under pressure and conduit means in communication with said source, conduit means for the discharge of said liquid, said means for rigidly connecting each of said synchronizing pistons with a corresponding heat engine piston consisting of a piston rod, said piston nods being provided with grooves for connecting said chambers with said conduits to adjust the amount of said liquid in said LAURENCE V. E'FN'ER, Primary Examiner. ROBERT M. WALKER, Examiner. 

1. IN A TWIN CYLINDER HEAT ENGINE HAVING A FIRST CYLINDER AND A SECOND CYLINDER AND TWO OPPOSED DRIVING PISTONS IN EACH OF SAID CYLINDERS WITH THE TWO DRIVING PISTONS OF ONE CYLINDER ADAPTED TO MOVE SIMULTANEOUSLY TOWARD EACH OTHER WHILE THE TWO DRIVING PISTONS OF THE OTHER CYLINDER ARE MOVING SIMULTANEOUSLY AWAY FROM EACH OTHER AND VICE VERSA, A DEVICE FOR SYNCHRONIZING THE MOTIONS OF SAID PISTONS WHICH COMPRISES, IN COMBINATION, A PAIR OF CYNCHRONIZING CYLINDERS DISPOSED IN LINE WITH EACH OF THE HEAT ENGINE CYLINDERS, ON OPPOSITE SIDES THEREOF, A SYNCHRONIZING PISTONS IN EACH OF THE SYNCHRONIZING CYLINDERS, MEANS FOR RIGIDLY CONNECTING EACH OF SAID SYNCHRONIZING PISTONS WITH A CORRESPONDING HEAT ENGINE PISTON, RESPECTIVELY, SO AS TO DIVIDE EACH SYNCHRONIZING CYLINDER INTO TWO CHAMBERS, A FIRST ONE AND A SECOND ONE, TRANSFER CONDUIT MEANS FORMING A CONSTANTLY OPEN COMMUNICATION BETWEEN ONE CHAMBER OF EACH CYNCHRONIZING CYLINDER LOCATED ON ONE SIDE OF ONE OF SAID HEAT ENGINE CYLINDERS AND ONE CHAMBER OF THE SYNCHRONIZING CYLINDER LOCATED ON THE OTHER SIDE OF THE OTHER OF SAID HEAT ENGINE CYLINDERS, AND TRANSFER CONDUIT MEANS FORMING A CONSTANTLY OPEN COMMUNICATION BETWEEN THE OTHER CHAMBER OF EACH SYNCHRONIZING CYLINDER LOCATED ON ONE SIDE OF ONE OF SAID HEAT ENGINE CYLINDERS AND ONE CHAMBER OF THE SYNCHRONIZING CYLINDER LOCATED ON THE SAME SIDE OF THE OTHER OF SAID HEAT ENGINE CYLINDERS, SAID CHAMBERS AND SAID TRANSFER CONDUITS BEING FILLED WITH A VIRTUALLY INCOMPRESSIBLE LIQUID. 